Dynamo-electric machine



Sept. 14,192

H. BARNES DYNAIO ELECTRIC MACHINE Filed Sept. 9, 1924 2 SheetsSheet 1 w/zwmi Ma 4770mm Sept: 1926. 1,599,631 H. BARNES ammo ELECTRIC momma Filed Sept 9,. 1924 2 Sheets-Sheet 2 W s Arm/Min" Patented "Sept. 14, 1926.

UNITED STATES PATENT OFFICE.

HERBERT BARNES, OF LONDON, ENGLAND, ASSIGNOR TO THE ENGLISH ELECTRIC COMPANY LIMITED, or LONDON,

:ENGLAND, A BRITISH COMPANY.

DYNAMO-ELECTRIC MACHINE.

. Application filed September 9, 1924, Serial No. 736,736, and in Great Britain November 9, 182 3.

In certain types of dynamo electric machines having a winding distributed around the periphery of one element of the machine there exists the characteristic that, although the winding. may be uniformly distributed, the current flowing therein is not uniform, being of a higher value in certain parts of the winding than in others. This want of uniformity is, in general, due to the fact that the winding carries two or more component currents differing in value or kind, this difference in conjunction with the methods of leading the currents into and out of the windings having the effect of producing resultant currents of hi h values in certain parts of the Winding an low values in other parts.

An example of a machine element having the features above indicated is found in the armature of a synchronous rotary converter. In this case the turns of the winding adjacent to the tappings by which the alternating current circuits are connected with the armature carry heavier currents than the parts more remote from these points.

A result of this non-uniform distribution of current is the production of non-uniform heating of the machine, the output of which is of course limited by the temperature rise of the hottest point so that the output is lower for the generation of a given amount of heat in the case where this is distributed non-uniformly than in the case where an approximately uniform distribution exists.

\Vith the object of rendering more uniform the distribution of the heating in the armature of a synchronous rotary converter, it has been proposed in the ap lication of Schroeder Serial No. 7 36,723, fi ed September 9, 1924, to arrange that the section of the armature conductor is varied from point to point around the core so that the greater section occurs where the higher effective current values are found whereby the resistance loss taking place in the different conductors is rendered more uniform.

The present invention relates to the proportioning of the dimensions of the slots and teeth of the armature of a synchronous rotary converter in which such a variation in the section of the conductor is made and in accordance with the invention this proportioning is carried out in such a way that any material variation in the local reluctance of the path for the magnetic flux for a given position under the pole face as the different teeth move past that point is avoided. Such a variation would be liable to produce local currents in the short circuited windings, which are usually arranged in the pole face of a rotary converter for the purpose of damping or starting, unless special steps were taken to prevent their occurrence. In a rotary converter arranged in accordance with the present invention it is possible to utilize a short circuited polo face \YlIlilllig of the ordinary type in con unction with an armature conductor arrangement in which the section is varied tor is employed in connection with rotary converters having the armature winding ar ranged in slots of constant depth distributed around the core, the width of the slots will in general be varied in accordance with the grading of the conductor.

An example of the invention applied to such a case will now be described with reference to the accompanying drawings. Fig ure 1 shows diagrammatically an end view of a part of the slotted circumference of the armature of a six pole rotary converter without any winding and with one pole and pole shoe of the associated field system.

Figure 2 shows a developed circumferential view of some of the armature slots as well as several armature coils placed in position therein. Figure 3 is a sectional View of one of the armature slots of a rotary converter not provided with the graded winding. Four conductors are shown in the slot. Figures 4 and 5 show by comparsion similar views of two slots and their associated conductors suitable for use in the armature of the same rotary converter after providing it with a graded armature winding arranged as in Figures 1 and 2.

In Figures 1 and 2 the six pole armature v 1. One of the six poles 1s deaving a pole shoe The ninety re arranged around the in eighteen groups LLll group occupyees oi the armature cc of each five are tr: are Wide slots 5. uing scheme vvill be clear exaniina on of Figure 2 xvhrrein conductc shown h heavy the Wide slots 5 of live e; siiitv shown h ed in the Fair-- rev U to Figure t). 'cih are tapped at points 13 r tervals 0''? cl v electrical deg to .nninncr. The pa e vvi'le conductori t3 the p tor. t i leadir fact ich is the usual case in ind with the t vpe ot winding shown e conductors vvhic currents in Figure 2 :ection oi rotathe tapping tht Title con- 1g assumed thatdirc tion of the usual manner h pit autacem ilorni but is varied i i not:n'ithstainhng the v (nth part of the it constitutes a is approximately the same and tooth and thus niare local reluctance of the ic than through the teeth 1 under the pole face is my invention and desire Patent is rotary converter, a an arniature, the latter core, a vinding in the JOIS leading to commusponds to Figure the arnnzture contains s i 3 'ant rr )RS to acconin'iodate the said variation in on. and the pr iportioning of slots and teeth being carried out in such a vay that material variation in the local reluctai through the '1 ven position nude a pole face aid held structure avoided.

:2. In a synchronous rotary converter, a field structure and van armature, the latter compir ng a slotted core a Winding in the slots having connectors leading to con'unutator segments and serving tor thepassage of di ct current and having tappings for the passage of alternating currents, the section or t e coiuluctors of which the armature Handing is termed being varied from point point in such a way that the greater section is tound near the points at which the ta") s for the alternating currents are er where the higher effective current var es e 3st, the said conductors being accommodated in slots of uniform depth and varying width, the width of the teeth being also varied so that at all points of the armature periphery the tooth pitch measured thereon contains approximately the same prop rtions of slot and tooth.

3. In arotar converter, a field structure having poled, an a mature having a slotted core, the slots being of varied widths and spaced apart. varied distances, thereb torming teeth of varied \vidths between the slots, the widths of ad acent slots and the distance between them being so proporti fined that any given tooth pit c1 on the periphery of i v the same to tooth as anv other tooth pitch, v providing a sun 'antiallv constant :ititat reluctance in the path otthe magnetic llux through the teeth for any given p0, -t-ion under a pole face.

[In testimony whereof I atlix nrv. signature.

HERBERT BARNES.

ratio o 1 slot 

